The present invention relates to a motor-driven compressor.
Japanese Laid-Open Patent Publication No. 2003-120555 describes a motor-driven compressor including a compression unit and a motor. The compression unit includes a fixed scroll and a movable scroll, which is capable of orbiting the fixed scroll. The motor orbits the movable scroll. Further, the motor-driven compressor includes a compression chamber defined by the fixed scroll and the movable scroll. The motor-driven compressor orbits the movable scroll to compress low-pressure fluid, which is drawn into the compression chamber, and discharges compressed high-pressure fluid.
Further, Japanese Laid-Open Patent Publication No. 2003-120555 describes a motor-driven compressor and an air-conditioner that includes the motor-driven compressor. The motor-driven compressor includes an injection port that draws in intermediate-pressure fluid, which has a higher pressure than the low-pressure fluid. The air-conditioner includes an injection pipe, which is connected to the injection port of the motor-driven compressor, and a gas-liquid separator, which is connected to the injection pipe. In the air-conditioner, intermediate-pressure fluid is obtained by the gas-liquid separator. The intermediate-pressure fluid flows through the injection pipe and the injection port and enters the compression chamber.
In the above structure, when the motor-driven compressor stops operating, the residual intermediate-pressure fluid in the injection pipe may enter the compression chamber through the injection port. This may cause the movable scroll to orbit in a reverse direction opposite to the forward direction. In such a case, the movable scroll will rotate a rotor of the motor in a reverse direction opposite to the forward direction.
When the rotor is rotated in the reverse direction, activation of the motor-driven compressor may be suspended until the reverse rotation of the rotor stops. However, it may take time until the reverse rotation of the rotor stops. This would increase the time required to activate the motor-driven compressor and lower the responsiveness of the motor-driven compressor.